When internal short circuit occurs to the traditional lithium battery, since a large amount of heat is released in a short time, the separator for which the material is polyolefin in the structure is melted and deformed due to an inability of the separator to withstand high temperature. If local heat accumulation cannot be blocked or internal short circuit cannot be stopped, then the active substance of the lithium battery is decomposed and forms a high-pressure gas, and may even generate a hazard such as explosion. Accordingly, all international lithium battery manufacturing firms invest significant resources into the research on the safety issue of how to effectively alleviate internal short circuit of the lithium battery. The heat-resistance layer (HRL) developed by Panasonic can be introduced to the inside of the lithium battery, thereby strengthening the mechanical properties of the separator and thus preventing the effect of internal short circuit generated by direct contact between the positive and negative electrodes caused by heating of the battery. As a result, the safety of the battery is increased. However, the thermal barrier material is mainly composed of a high content of inorganic particles and a low content of an organic polymer binder, and thus internal resistance of the battery is readily increased. Moreover, the inorganic particles are readily peeled off when used in a charge/discharge process, and therefore the protective function thereof is lost. Moreover, since the inorganic particles are readily aggregated and subsided, processability is inconvenient. As a result, the effect of the thermal barrier material is affected.
Based on the above, currently, a new material composition is still needed to improve the impedance of the current commercial battery containing a thermal barrier layer, and to provide good processability and maintain the safety of the battery.